When NASA was considering animals to experiment on in space, they picked birds, because of the low maintenance. Although NASA was aware that most birds require gravity to swallow and would not survive the weightlessness of space, they did manage to find two types of bird that would survive the trip.
Which birds were they?

Answer

Doves and Pigeons.
Since most birds swallow water by tilting their heads back and using gravity to let the water run down their throats, they would dehydrate in space. Doves and Pigeons are the only birds that can drink without tilting their heads back.Hide

BORING!!! I don't know wherit is boring!! This is a highly informative teaser! I knew that birds need gravity to swallow but i didn't know that those two species were exception!! Thanx Keep submitting this kind of teasers. They truly work.

According to the Dove Page (http://www.dovepage.com/keeping/), and they should know, the main difference between the two is that larger birds tend to be called pigeons, and smaller birds tend to be called doves.